Study On Plugging Mechanism And Chemical Blockage Removal Of Water Injection Well In Oil Field

Nowadays, most of the offshore oil fields have entered the mid-and late, and the major oil fields are being into the high water cut stage. In water-flooded oil fields, although the injection allocation rate of single well increased after using high duty pump, but water-injection intake level plug problem, leading to high injection pressure, huge energy consumption and difficult water injection, obviously restricted the stable production and further enhancing oil recovery of the oil field.Offshore oil platform service life is generally not more than 20 years, which is shorter than onshore oilfield development life. After an oilfield enters into a high water cut stage, in order to stabilize oil production, improving injection flow rate and maintaining higher formation pressure were the inevitable measures for increasing fluid production of waterflooded oil field. And acidizing treatment was implemented once half a year on average for purpose of ensuring normal operation of waterflooding, otherwise the water-injection intake level plug problem will seriously affect the normal production of oil field. However acidizing treatment can not resolve the plug problem fundamentally, and the validity period of acidification will gradually become shorter along with the increase of acidizing operations. Therefore, it is necessary to analyze the plugging mechanism and the influence of the injection process, put forward the intensified injection measures of injection wells.This study analyzed the plugging mechanism and the influence of the injection process from the perspective of the characteristics of the reservoir, and proposed the corresponding intensified injection measures of injection wells according to the plugging types. This study laid the theory and equipment fundaments for intensified injection of injection wells, basing on the feasibility study and the safety evaluation technology research of removing blockage and enhancing water injection, researching on the plugging removal technology,determining the rational indexes for water injection, etc.According to the results of scale inhibitors adsorption experiments of typical oilfield and the anti-scaling effects, this study selected two type of scale inhibitors:BHF-03 and HFG-5, which have characteristic of less adsorbed quantity and better scale-preventing performance. For the two kinds of optimal scale inhibitors, this research evaluated their operating distance against the short range disadvantage of conventional injection method. The result of laboratory experiment indicates that, it has better anti-scaling effect using high concentration scale inhibitors plug injection mode before the traditional scale inhibitors injection operation, which make formation fully absorb scale inhibitors in near bottom-hole area.